JP3050903B2 - Acrylate copolymer - Google Patents

Description

Description: The present invention relates to acrylate copolymers, aqueous polyacrylate dispersions of polymers and to a process for preparing the same.

There is a great need for stable polyacrylate dispersions having good film-forming ability, high tensile strength values and effective water resistance for use as paint binders. The use of comonomers to improve some of the above properties of the dispersion can adversely affect other properties. For example, U.S. Pat.No. 4,104,220 which improved the water resistance of acrylate copolymers under high humidity conditions and the adhesion of latexes containing them to various substrates
Certain water-soluble allyl-containing monomers described in U.S. Pat. No. 4,111,877 have high chain transfer constants. The tendency of these monomers (commonly known as wet-adhesive monomers) to undergo chain transfer will significantly reduce the latex polymer chain length, which can be attributed to aqueous polyacrylate dispersions containing such acrylate copolymers. Evident by the low equivalent viscosity (RSV) of the liquid,
The basis for this is a decrease in molecular weight due to carbon chain length as opposed to molecular weight due to branching.

U.S. Pat.No. 4,659,771 discloses that a stable aqueous polyacrylate dispersion can be obtained in the presence of protective colloids when relatively small amounts of substantially completely water-soluble monomers having conjugated unsaturated bonds are present. ing. Further, European Patent Application Nos. 252,526 and 331,011 disclose, in either the presence or absence of comonomers, including allyl monomers in which small amounts of water-soluble monomers having conjugated unsaturated bonds are soluble in organic solvents. It discloses that an aqueous polyacrylate dispersion can be stabilized in the absence of a protective colloid. RS of such polyacrylate dispersion
V is comparable to the RSV of a conventional polyacrylate dispersion.

There is a need for polyacrylate dispersions with large carbon chains, correspondingly high molecular weight, improved water resistance and improved processability.

According to the present invention, an acrylate copolymer having a repeating unit derived from an acrylic or methacrylic monomer and a water-soluble monomer having a conjugated unsaturated bond has about 0% of the repeating unit based on the weight of the entire copolymer. .
1-3% is derived from a water-soluble monomer having a conjugated unsaturated bond, that is, the copolymer contains repeating units derived from a water-soluble allylic monomer in weight of the whole copolymer. About 0.1 to 3% based on the

The acrylate copolymers of the present invention have low viscosity, are mechanically stable, and form aqueous polyacrylate dispersions with improved film toughness and transparency. These copolymers are latex paints, binders for non-woven materials,
Useful for the production of aqueous inks, paper coatings and aqueous adhesives such as pressure sensitive adhesives. further,
Latex polymer molecular weight increases significantly, as indicated by measurement of reduced specific viscosity (RSV). Latex paints made with these dispersions have excellent gloss and wet adhesion.

The water-soluble allylic monomer useful in the present invention is an allyl-containing compound having a solubility of at least 0.5 g / 100 g of water at 20 ° C., preferably at least 1.0 g / 100 g of water at 20 ° C. Called). All such water-soluble allylic monomers have at least one polar functional group (eg, hydroxy, ester, ether, urethane, ureide, etc.). Examples of such monomers are allyl alcohol, mono-, di- and tri-allylamine and their corresponding acid salts; and the alkyl derivatives of mono-, di- and tri-allylamine and their corresponding acid salts. Allyl amides, allyl carbonates, allyl carbamates and their derivatives, epoxide monoallyl and diallylamine adducts are also useful, with preferred monomers being allyl urea and, for example, Sipomer WAM [Alcolac, Inc. Maryland. Allyl derivatives of cyclic ureido compounds, such as N- (allylcarbamate) aminoethylimidazolidinone (Air Prodncts and Chemicals, Inc.) Allen, PA Available from the town under the trademark WAM IV)
The latter is particularly preferred, which is described in U.S. Pat.
No. 1,877. The copolymer may optionally also include other free radical copolymerizable monomers.

"Water-soluble" for monomers with conjugated unsaturated bonds
The term is at least 0.4g / 100m water at room temperature (about 20 ℃)
1, preferably having a solubility of 1.0 g / 100 ml of water.

Water-soluble monomers having a conjugated unsaturated bond, i.e., a conjugated double or conjugated triple bond, suitable for use in the practice of the present invention are described in the above-mentioned European Patent Applications 252,526 and 3
31,011. These include furonic acid, C4-C36 linear or cyclic non-aromatic sulfonic acids, rosin or C5-C36 carboxylic acids or C4-C36.
Metal, amine, ammonium or quaternary salts of linear or cyclic non-aromatic sulfonic acids
t), and their water-soluble derivatives.

Such derivatives include water-soluble amine salts, amides, substituted amides, hydroxyalkyl esters, sulfoalkyl esters, aldehydes and alcohols of the monomers. Thus, such monomers include, for example, sorbic acid, cinnamic acid, abietic acid, linoleic acid, furylacrylic acid, muconic acid, 5-formyl-2-fural-sulfonic acid, and derivatives of furonic acid. Suitable metals that form the metal salts of rosin, carboxylic acids and sulfonic acids include sodium, potassium, lithium, magnesium, calcium and zinc.

Preferred sulfonic acid monomers are water-soluble cyclic non-aromatic sulfonic acid monomers having a conjugated unsaturated bond having 4 to 24 carbon atoms. Preferred sulfonic acid salts are salts of sulfonic acids having 4 to 24 carbon atoms and water-soluble derivatives thereof.

"Cyclic non-aromatic" with respect to sulfonic acid means that the conjugated unsaturated moiety is present as part of the cyclic structure and is polymerized by free radical polymerization in 1.4 form (i.e., the cyclic structure is Not inert to free radicals such as phenyl, imidazolyl and pyrrolyl structures). Examples of such moieties are 5- to 8-membered rings consisting entirely of carbon atoms or containing one or more heteroatoms such as, for example, nitrogen, oxygen or sulfur atoms. A five-membered ring having a carbon, sulfur or oxygen atom as the fifth atom is preferred, with cyclopentadienyl, furanyl and thiophenyl being most preferred.

Examples of free-radically polymerizable sulfonic acids useful in the present invention have the general formula: Wherein R ₁ and R ₆ and, if present, R ₂ , R ₃ , R ₄ , R ₅ are -COOH, -COOR ₇ , -SO ₃ M, -R ₈ SO ₃ M or substituted or unsubstituted Alkyl, aryl or alkaryl;
R _1, R ₂ present, R _3, R _4, one of R ₅ and R ₆ is -SO ₃ M or -R ₈ SO ₃ M; R ₇ is a substituted or unsubstituted alkyl, aryl or alkaryl R ₈ is a substituted or unsubstituted alkylene (eg, methylene, ethylene, etc.), arylene, aralkylene, alkylarylene, alkyl, aryl and arylalkyl; M neutralizes the H, —SO ₃ charge A stoichiometric equivalent of a metal ion, or an amine, ammonium or quaternary ammonium group in an amount sufficient for one or both of the double bonds to be replaced by a triple bond (in this case, , R ₂ and R ₃ , R ₄ and R ₅ , or R _2-5 are not present)] or a formula: Wherein R ₂ , R ₃ , R ₄ and R ₅ are as defined above, and R ₂ ,
At least one of R ₃ , R ₄ and R ₅ is -SO ₃ M or -R
₈ SO ₃ M; R ₈ and M are as defined above; y is 5
One or more substituted or unsubstituted carbons or heteroatoms to form a membered ring to an eight-membered ring]. Formula I
Only one of R _{1 to} R ₆ of formula II and only one of R _{2 to} R ₅ of formula II
It is preferably SO ₃ M or —R ₈ SO ₃ M.

Allyl monomers and conjugated monomers readily copolymerize with acrylic and methacrylic esters.

Representative acrylates and methacrylates used in the present invention include substituted and unsubstituted alkyl, aryl, and alkaryl esters of acrylic acid and methacrylic acid. The acrylate and methacrylate used in the production of the improved latex according to the present invention are preferably alkyl esters having an alkyl group of up to 9 carbon atoms, and include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl acrylate and isopropyl. Methacrylate, n-butyl acrylate, n-butyl methacrylate,
Isobutyl acrylate, isobutyl methacrylate, 2
-Ethylhexyl acrylate, 2-ethylhexyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 3,3-dimethylbutyl acrylate, and 3,3
Most preferably-dimethylbutyl methacrylate.

Other alkyl esters of acrylic acid and methacrylic acid having up to 22 carbon atoms that can be used in the present invention include decyl acrylate, decyl methacrylate, hendecyl methacrylate, lauryl methacrylate, tridecanyl methacrylate, myristyl acrylate, myristyl methacrylate, Pentadecanyl methacrylate, arachidyl methacrylate, behenyl methacrylate, 10-methylhendecanyl methacrylate, and 2-ethyl-
There is lauryl methacrylate.

Esters of acrylic acid and methacrylic acid suitable for use in the present invention are usually homopolymerizable or copolymerizable with each other, or substituted or unsubstituted styrene, acrylic or methacrylic acid; vinyl halide Vinylene halides; vinylene halides; allyl esters of saturated monocarboxylic acids; vinyl esters, vinyl ethers and dialkyl esters of monoethylenically unsaturated dicarboxylic acids, ethylenically unsaturated monocarboxylic acids and ethylenically unsaturated polycarboxylic acids; Copolymerizable with one or more different comonomers that are addition polymerizable, including compounds, nitriles, unsubstituted and substituted (including N-substituted) amides.

In the acrylate copolymer according to the present invention, units derived from acrylate or methacrylate monomers preferably account for 50% by weight of the entire copolymer. However, comonomer units capable of free radical polymerization include units derived from acrylates or methacrylates and comonomer units (ie, repeating units derived from a monomer having a conjugated unsaturated bond and repeating units derived from a water-soluble allylic monomer). Unit), optionally from about 0.5% to less than 75% by weight, preferably from 0.5 to 50% by weight, most preferably from about 1 to about 10% by weight
May be present in amounts.

The expression "total weight of the copolymer" as used herein means the total weight of units derived from alkyl esters of acrylic or methacrylic acid, conjugated and allyl monomers capable of free radical polymerization and all other comonomers. . This proportion (%) is proportional to the proportion (%) of the total monomers used to form the copolymer or dispersion.

Vinyl esters copolymerizable with acrylates and methacrylates used in the process according to the invention include, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate,
There are aliphatic vinyl esters such as vinyl valerate and vinyl caproate. Allyl esters of saturated monocarboxylic acids include, for example, allyl acetate, allyl propionate and allyl lactate. These comonomers are preferably used in amounts up to about 10% by weight of the total monomers. The allyl esters of saturated monocarboxylic acids are generally used in relatively small amounts with large amounts of one or more other vinyl comonomers, especially with aliphatic vinyl esters such as, for example, vinyl acetate.

Vinyl ethers which can be copolymerized with the acrylates and methacrylates used in the process according to the invention include methyl vinyl ether, ethyl vinyl ether and n-butyl vinyl ether, typical vinyl ketones being methyl vinyl ketone, ethyl vinyl ketone and isobutyl vinyl ketone. is there. Suitable dialkyl esters of monoethylenically unsaturated dicarboxylic acids include diethyl maleate, dibutyl maleate, dioctyl maleate, diisooctyl maleate, dinonyl maleate,
There are diisodecyl maleate, ditridecyl maleate, diprol fumarate, dibutyl fumarate, dioctyl fumarate, diisooctyl fumarate, didecyl fumarate, dibutyl itaconate and dioctyl itaconate.

Monoethylenically unsaturated monocarboxylic acids suitable for use as comonomers are acrylic acid, methacrylic acid, ethacrylic acid, and crotonic acid, and monoethylenically unsaturated dicarboxylic acids are, for example, maleic acid, fumaric acid, itaconic acid and The citraconic acid is a monoethylenically unsaturated tricarboxylic acid such as aconitic acid, and halogen-substituted derivatives of these acids such as α-chloroacrylic acid and anhydrides such as maleic anhydride and citraconic anhydride are also used. Are suitable.

The corresponding nitriles of such acids that can be used as comonomers include acrylonitrile, α-chloro-acrylonitrile and methacrylonitrile. Suitable amides of such acids include, for example, unsubstituted amides such as acrylamide, methacrylamide, other α-substituted acrylamides, and amides of the above mono- or polycarboxylic acids and aldehydes such as formaldehyde. There are N-substituted amides obtained by the usual reaction of Suitable N-substituted amides include N-methylolacrylamide, N-methylolmethacrylamide, alkylated N-methylolacrylamides such as N-methoxymethylacrylamide and N-methoxymethylmethacrylamide and alkylated N-methoxymethylmethacrylamide. There is.

Amino compounds which can be used as comonomers include substituted and unsubstituted aminoalkyl acrylates, hydrochlorides and methacrylates of amino monomers, such as β-aminoethyl acrylate, β-aminoethyl methacrylate, dimethylamino methacrylate, β-dimethylaminoethyl acrylate, There is dimethylaminomethyl methacrylate. Suitable hydroxy-containing monomers include β
-Hydroxyethyl acrylate, β-hydroxypropyl acrylate, γ-hydroxypropyl acrylate and β-hydroxyethyl methacrylate.

Although protective colloids can be used in the method of the invention, the presence of a protective colloid is not necessary to achieve the objectives of the invention.

Anionic, cationic, nonionic and amphoteric surfactants known in the art and mixtures thereof can be used in the method of the present invention. These surfactants are usually used for emulsion polymerization, but are not always necessary for producing the copolymer of the present invention.

Conventional emulsion polymerization methods can be used, including both semi-batch or continuous types and thermal, thermal redox or adiabatic redox methods.

The following examples further illustrate the invention. All parts and percentages are by weight unless otherwise indicated.

Example 1 This example illustrates one embodiment of the present invention. In a reactor equipped with a stirrer, reflux condenser, thermometer, three supply ports and a water jacket, 20.3 parts of distilled water, 0.5 part of potassium sorbate, and N-2- (allyl carbamate) aminoethylimidazolidinone [WAM IV , Air products] was charged with stirring. The reaction mixture is heated to 85 ° C. with circulating hot water, at which time the three feeds are: (1) 6 parts of distilled water + 4
% Aqueous formaldehyde-sodium sulfoxylate 1
Parts: (2) 6 parts of distilled water + t-butyl peroxide (90 parts)
%) 0.1 part; and (3) poly (oxy-1,2-ethanediyl) α-sulfo-ω- (nonylphenoxy) ammonium salt (Alipal co-436, GAF Corp., New York, NY) 1.6
Parts, distilled water 14 parts, pre-emulsion consisting of 50 parts of a monomer mixture containing 50 parts by weight of butyl acrylate, 50 parts by weight of methyl methacrylate and 1.0 part by weight of methacrylic acid,
While maintaining the temperature at 85 ° C., the reactor was metered in over 3.5, 3.5 and 3.0 hours, respectively. When heating was continued for 30 minutes after the last addition of initiator, the reactor was cooled and the properties of the latex formed were determined.

The latex has a solids content of 0.25 in N-methylpyrrolidone.
% By weight, and the viscosity at room temperature (25 ° C.) was measured with a capillary viscometer, and the converted specific viscosity was measured by comparing with a control sample containing no latex.

Example 2 The procedure of Example 1 was repeated, but in this case N-2-
(Allyl carbamate) Instead of aminoethylimidazolidinone, 0.2 parts of allyl urea and 0.3 parts of water were used.

Example 3 20.3 parts of distilled water was placed in a reactor equipped with a stirrer, reflux condenser, thermometer, 3 feed ports and a water jacket.
0.5 parts of potassium sorbate and N-2- (allyl carbamate) aminoethylimidazolidinone (WAM IV,
0.5 parts [allyl urea] [0.1 parts [allyl alcohol] [alloxy-propanediol [diallyl tartardiamide]] were charged with stirring. The reaction mixture is heated to 85 ° C. with circulating hot water, at which time three feeds are used: (1) 6 parts of distilled water + 1 part of 4% aqueous sodium formaldehyde sulfoxylate; (2) 6 parts of distilled water + t-butylhydrogen. Beloxide (90%) 0.1
And 1.6 parts of poly (oxy-1,2-ethanediyl) α-sulfo-ω- (nonylphenoxy) ammonium salt (Aripearl Co-436, Gaff Corporation, New York, NY) [sorbic acid, allylamine 0.2 part (sorbic acid A pre-emulsion consisting of 50 parts of a monomer mixture containing 14 parts of distilled water, 50 parts by weight of butyl acrylate, 50 parts by weight of methyl methacrylate and 1.0 part by weight of methacrylic acid to neutralize and solubilize the allyl ammonium salt)) While maintaining the temperature at 85 ° C., the reactor was metered over 3.5, 3.5 and 3.0 hours, respectively. When heating was continued for 30 minutes after the last addition of initiator, the reactor was cooled and the properties of the latex formed were determined.

0.38 parts of sorbic acid, 0.2 parts of allylamine in place of both potassium sorbate and N-2- (allyl carbamate) -aminoethylimidazolidinone (to neutralize and solubilize sorbic acid as its allyl ammonium salt) The procedure of Example 1 was repeated except that 0.1 part of allyl alcohol and 0.32 part of water were used.

Example 4 The procedure of Example 1 was repeated, except that 0.2 g of alloxypropanediol and 0.3 g of water were used instead of N-2- (allyl carbamate) aminoethylimidazolidinone.

Example 5 The procedure of Example 2 was repeated except that 0.2 g of diallyl tartardiamide was used instead of allyl urea.

Example 6 The procedure of Example 3 was repeated except that 0.1 part of water was used instead of allyl alcohol.

Example 7 N-2- (allyl carbamate) aminoethylimidazolidinone was removed from the initial charge and 1.0 part of N-2- (allyl carbamate) aminoethylimidazolidinone was added to the pre-emulsion.

Example 8 The procedure of Example 1 was repeated except that 14 parts of distilled water was added to the initial charge rather than to the pre-emulsion.

Example 9 A 5% aqueous viscosity of 75 centipoise (25 ° C) and a hydroxyethyl molar substitution of 2.5 (anhydroglucose 15
Example 1 was repeated except that the initial reactor charge was added to 0.3 parts of hydroxyethyl cellulose (HEC) having an average number of hydroxyethyl groups per unit).

Example 10-Comparative The procedure of Example 2 was repeated except that 0.2 parts of water was used instead of allyl urea.

Example 11-Comparative The procedure of Example 1 was repeated except that 0.5 parts of water was used instead of potassium sorbate.

Example 12-Comparative The procedure of Example 10 was repeated, except that 0.5 parts of water was used instead of potassium sorbate.

From the data shown in Table 1, the RSV value shows that the latex polymer molecular weight due to the increase in chain length is lower in the latex produced in the presence of both the water-soluble allyl monomer and the water-soluble conjugated unsaturated monomer. (Example
It is found to be significantly larger than the latex prepared in the presence of either 10) or the water-soluble conjugated unsaturated monomer alone (Example 11) or in the absence of both components (Example 12).

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Harry Joseph Goldie, Clam Creek Drive, Woodlin 19094, Pennsylvania, USA 129 (56) References JP-A-63-27513 (JP, A) JP-A Sho 59-179511 (JP, A) JP-A-2-70714 (JP, A) JP-A-62-270410 (JP, A) JP-A-1-268746 (JP, A) (58) Fields investigated (Int. Cl ^7, DB name) C08F 220/10 -. 220/20 C08F 20/10 - 20/20 C08L 33/00 - 33/16 C09D 133/00 - 133/16

Claims (10)

(57) [Claims] 1. An acrylate copolymer comprising a repeating unit derived from an acrylate monomer or a methacrylate monomer and a repeating unit derived from a water-soluble monomer having a conjugated unsaturated bond, wherein the entire copolymer 94 to 99.8% of repeating units derived from acrylate and / or methacrylate monomers, 0.1 to 3% of repeating units derived from a water-soluble monomer having a conjugated unsaturated bond, and A water-soluble monomer having a conjugated unsaturated bond comprising about 0.1 to 3% of a repeating unit derived from an allyl monomer; a furancarboxylic acid; a linear or cyclic non-aromatic having 4 to 36 carbon atoms having a conjugated unsaturation; Aromatic sulfonic acids; abietic acid and neoabietic acid; carboxylic acids having 5 to 36 carbon atoms having conjugated unsaturation; and metal salts of these acids; Wherein the water-soluble allylic monomer is selected from the group consisting of mine salts, ammonium salts, quaternary salts, amides, substituted amides, hydroxyalkyl and sulfoalkyl esters; and aldehydes and alcohols having 5 to 36 carbon atoms having a conjugated unsaturated bond. Allyl alcohol and acid salts of allyl alcohol; monomers, di- and tri-allylamines and their acid salts; alkyl-substituted mono-, di- and tri-allylamines and their acid salts; allyl amide; allyl carbonate; An acrylate copolymer selected from the group consisting of epoxide mono- and di-allylamine products; allyl urea; allyl-substituted cyclic ureides; and N-2- (allyl carbamate) aminoethylimidazolidinone. 2. The acrylate according to claim 1, wherein the allylic monomer has a solubility of at least 0.5 g in 100 g of water at 20 ° C. and further comprises a hydroxide, ester, ether, urethane or ureide group. Copolymer. 3. A water-soluble allylic monomer having a water content of 10 at 20 ° C.
3. The acrylate copolymer of claim 2, further having a solubility of at least 1.0 g in 0 g. 4. The carboxylic acid is sorbic acid, cinnamic acid, abietic acid, linolenic acid, furylacrylic acid or muconic acid, and the sulfonic acid is 5-formyl-
The acrylate copolymer according to any one of claims 1 to 3, further comprising 2-furalsulfonic acid. 5. The monomer having a conjugated unsaturated bond is cyclic,
Further characterized in that it is a non-aromatic sulfonic acid, wherein the conjugated unsaturated moiety is present as a 5- to 8-membered ring consisting solely of carbon paper or a 5- to 8-membered ring containing nitrogen, oxygen or sulfur atoms. Item 5. The acrylate copolymer according to any one of Items 1 to 3. 6. The acrylate copolymer according to claim 5, wherein the 5-membered ring forms a cyclopentadienyl, furanyl or thiophenyl group. 7. The acrylate copolymer according to claim 1, wherein the metal salt of the acid is a sodium, potassium, lithium, magnesium, calcium or zinc salt. (A) at least one water-soluble monomer having a conjugated unsaturated bond, about 0.1 to 3 of the total monomer content;
% By weight and (b) at least one water-soluble allyl monomer, a process for producing an acrylate copolymer comprising emulsion-polymerizing an acrylate or methacrylate in the presence of about 0.1 to 3% by weight of the total monomer content. A water-soluble monomer having a conjugated unsaturated bond is furan carboxylic acid; a linear and cyclic non-aromatic sulfonic acid having 4 to 36 carbon atoms having conjugated unsaturation; abietic acid and neoabietic acid; Carboxylic acids having 5 to 36 carbon atoms having unsaturation; metal salts, amine salts, ammonium salts, quaternary salts, amides, substituted amides, hydroxyalkyl and sulfoalkyl esters of these acids; and conjugated unsaturated bonds Wherein the water-soluble allyl monomer is selected from the group consisting of aldehydes and alcohols having 5 to 36 carbon atoms, Salt of allyl alcohol; mono- -, di- and tri - allylamine and their salts; mono- substituted with alkyl -, di -
Allylamide; allyl carbonate; allyl carbamate; epoxide mono- and di-allylamine adducts; allyl urea; allyl-substituted cyclic ureides; and N-2- (allyl carbamate) aminoethyl imidazo The acrylate copolymer described above, selected from the group consisting of lydinones. 9. (a) Acrylate and methacrylate are substituted or unsubstituted alkyls of acrylic acid and methacrylic acid, wherein the alkyl group has up to 22 carbon atoms.
(B) the water-soluble allyl monomer is allyl alcohol; mono-, di- and tri-allylamine and their acid salts;
Alkyl-substituted mono-, di- and tri-allylamines and their acid salts; allylamide; allyl carbonate; allyl carbamate; epoxide mono- and di-allylamine products; allyl urea;
A monomer selected from the group consisting of-(allyl carbamate) aminoethylimidazolidinone, having a solubility of at least 0.5 g in 100 g of water at 20 ° C; and (c) substantially complete with conjugated unsaturated bonds The preferred water-soluble monomer is furan carboxylic acid; abietic acid, neoabietic acid, metal salts, amine salts, ammonium salts and quaternary salts of carboxylic acids having 5 to 36 carbon atoms and sulfonic acids having 4 to 36 carbon atoms. A monomer selected from the group at 20 ° C
9. The method of claim 8, further having a solubility of at least 0.4 g / 100 mL of water. 10. An aqueous polyacrylate dispersion containing the acrylate copolymer according to claim 1.